Manufacture of ferrophosphorus.



Dawn I. MILLER, ornmmmenm.

MANUFACTURE F FERRQPHOSPHORUS.

1,115,471. Ito Drawing.

. To all whom it may concern:

Be it known that I, DAvn) I. MILLER, a

citizen of the United States, residing at' Birmingham, in the county of Jefferson and State of Alabama, have invented certain new and useful Improvements in the Manufacture of Ferrophosphorus; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

y invention relates to the manufacture of ferrophosphorus from natural com pounds containing iron and phosphorus, and by a blast-furnace process.

' So far as I am aware there are at present but two known and successfully practised methods of commercially producing ferrophosphorus, one of which, and the most expensive, requiring the use of an electrical furnace, the other and most practicable, as well as the least expensive, being by the use of the blast furnace. In both methods there are limitations as to the character of the materials that can be utilized for the manufacture of 'ferrophosphorus, and especially is this the case in the blast furnace process which, as heretofore practised, has demanded the use in the furnace charge either of a previously produced phosphorus-bearing" material, such as PhOSPhOIlC' slag, or the selection of such iron ore and phosphatic rock as would jointly contain the proper content of phosphorus, and silicious matter, or, in the absence of a proper content of silicious matter in the mixture of iron ore and phosphatic material, theaddition of such further quantity of silica to the char e of iron ore and phosphatic material as w ll produce a slag of the proper composition for successful smelting.

The present blast furnace methods of producing ferrophosphorus demand the use of a large quantity of phosphorus-bearing materials of a grade well adapted to and available for the manufacture of fertilizers, to the exclusion of a large quantity of phosphorus-bearing material which is not avail- -able for the manufacture of commercial.fer-

blast-furnace protilizers, and which the cess for themanufacture of ferrophosphorus as now practised, can not utilize.

Among the natural phosphorus-bearing materials at present useless-1n the manufacture of fertilizers and not available for the Specification of Letters Patent. Application filed May 6, 1914. Serial No. 886,637.

processes, enumerated as illustrative certain large sedimentary deposits of tribasic phosphates of lime, which are so overlaid. or agglomerated with highly silicious material as to be un- Patented Oct. 27, 1914;-

may be manufacture of ferrophosphorus by the 7 present blast-furnace profitable to work for commercial fertilizer purposes; also large deposits of apatite-'00:

currlng as intrusive veins in igneous rocks,

these veins frequently varying in width from a few inches to manyfe'et and the surrounding rock being acid in character, so that the large veins only can be profitably worked by present processes; also large deposits of the phosphateof alumina and iron ofwhich the essential components are phosphorus, iron, alumina and silica, there being only asmall trace of calcium or other basic material.

The object, therefore, of my present invention is the utilization, in" a blast furnace process for the commercial production of ferrophosphorus of any desired phorphorus content, of phosphorus-bearing materials of the character above noted which are not now available for use by existing blast furnace processes, but which, for the reasons stated, it is desirable and economical to use. e To this 'end, generally stated, my invention involves, in the manufacture commercially-of ferrophospho'rus by the blast furpace process, the addition to a charge of iron bearing material and phosphorus bear- -1ng ma rial of-a basic material in proper proportion to liberate the phosphorus required to combine with the iron, and subjecting the charge or mixture so constituted to the smelting process in a blast furnace.

In carrying out my. invention I take a given amount of a natural phosphate having the characteristics hereinbefore noted, also given amounts of iron ore, and coke or other fuel to constitute the charge, and by analysis ascertain the relative proportions of phosphorus, iron, acids and bases con; tained therein, and to this charge or mixture is added suflicient basic material to produce the proper proportion of bases to acids in the final mixture, which is then smelted by the usual blast furnace process.

For purposes of illustration I will assume that the ferrophosphorus to be produced is desired to contain fifteen (15). per cent. of phosphorus and to show on analysis a formula as follows: Fe 78.50%; P 15.00%; Mn

amount, in some cases a mere shown to contain: Fe 4.937

' alumina 0.16%; S 0.04%; C 3.30%; Si 3.00%. I will also assume that a phosphate rock is tobe utilized which will on analysis be a; P 13.20%; SiO, 18.09%; A1 0 24.00%;H O 16.49%; CaO+MgO 4.16%. I will also assume that the iron ore to be utilized on analysis will be shown to contain: Fe 39.15%; P 1.00%; Mn 0.10%; SiO, 30.00%; A1 0 3.42%; H O 5.71%; CaO-l-MgO 1.08%. And that the coke to be used in the charge *will on analysis be shown to contain: SiO 5.00%; A1 0, 3.50% H O 3.00%; CaO-l-MgO 3.50%; C 82.00%.

Experience has shown that the blast furnace charge should contain about 1.9 lbs. of coke for each pound of pig to be produced. Therefore, for the production of ferrophosphorus from the natural phosphate rock and iron ore referred to, for eveig 100 lbs. of pig to be produced containing fteen per cent. of phosphorus, the charge should contain: iron ore 186.2 lbs., phosphate rock 113.6 lbs., and coke 190 lbs. If it were attempted to use such a charge for the manufacture commercially of ferrophosphorus by the present known and practised blast furnace processes, while a certain amount of the acids and bases would flux there would yet remain an excess of acid in the. slag which would contain silica 57.65%; 29.40%; lime and magnesia 9.80%, a character of slag: that would render impossible the proper operation of the furnace.

To meet this condition I add tov the mixture or charge a base, preferably limestone, though other suitable basic material may be used, in proper proportion to liberate the about 53.54 lbs. in the hundred pounds,

will be silica 37.99%; alumina 19.7 6%;

required percentage of phosphorus. As sume that limestone is to be d that used an its contents as'found b analysis are SiO 0.60%; A120, 0.90%.; aO+MgO 54.61%-

As the proper ratio of acids to bases in the slag is approximately as 1.4 to -1, the available bases in the limestone would equal an therefore, about 134 lbs. of the limestone base would be required for each 100 lbs. of

the pig. The addition of this quantity of limestone would produce afinal mixture, as follows: iron ore 186.2 lbs; phosphate rock 113.6 lbs.; limestone 134 lbs.; coke 190 lbs. The approximate composition of the resultant ferrophosphoruspig produced by smelting this mixture will be Fe 78.50%; P 15%; Mn 0.16%; 313.00%; s 0.04%; 0 3.30%. The approximate composition of the 1slag 1me and magnesia 41.22%.

- Having thus described my invention, what I claim and desire to secure by Letters Patcut is:

The process of producing 'ferropho'sphoru's, which consists in charging a blast furnace with a mixture of iron bearing material, a phosphorus-bearing material, and a basic material in proper proportion to lib- 'erate the percentage of phosphorus required to combine with the iron, and smelting said mixture. V

In testimony whereof I aflix my signature, in the presence of two subscri witnesses.

. DAVID I. LER.

Witnesses:

CHAS. F. Hoeun, I A T. BaezELroN. 

